Various types of microphone systems have been used in various applications through the years. Microphones in these systems typically receive acoustic energy and convert this acoustic energy into an electrical voltage. This voltage can be further processed by other applications or for other purposes. For example, when used in a hearing instrument (e.g., a hearing aid) the microphone may receive acoustic energy, and convert the acoustic energy to an electrical voltage. The voltage may be amplified or otherwise processed by an amplifier, or by other signal processing electronics circuitry, and then presented by a receiver as acoustic energy to a user or wearer of the hearing aid. To take another specific example, microphone systems in cellular phones typically receive sound energy, convert this energy into a voltage, and then this voltage can be further processed for use by other applications in the cellular phone. Microphones are used in other applications and in other devices as well.
In many acoustic systems, noise can be a problem. For example, in hearing instrument systems, the noise of the wind can interfere with a received voice signal and this noise can make discerning the actual voice signal difficult.
Previous attempts have utilized multi-stage buffers to reduce noise. More specifically, the electrical signal produced by the microphone is filtered. Although these buffers have been somewhat successful in reducing noise, they sometimes also suffer from various shortcomings For example, since these devices have multiple stages, they can become large in size. The large size can be disadvantageous in applications where small parts are desired such as in hearing aids or in microelectronic applications.
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